Cognitive relaying and opportunistic spectrum sensing in unlicensed multiple access channels

Abstract

In this paper, a cognitive multiple access channel with one primary node and M secondary nodes is considered, and the impact of the following techniques on the stability region of the system is investigated: (i) relaying by the secondary nodes of the primary traffic (cognitive relaying); (ii) opportunistic spectrum sensing at the secondary nodes. Specifically, inner bounds on the stability region of the system for the case of M = 2 secondary nodes are derived by assuming cognitive relaying and both simultaneous and opportunistic spectrum sensing at the secondary nodes. The analysis is carried out by defining convenient systems which statistically dominate the original ones (dominant systems). Numerical results provide insight into the performance advantages of the different strategies in terms of stability region. © 2008 IEEE.